Tucked away high in 15,000-ft glaciated mountains, Chandratal, the only sacred lake in the Lahaul-Spiti district of Himachal Pradesh, has for long been steeped in mythology. Legend has it that the crescent-shaped pristine water body is an abode of fairies who descend on Earth on moonlit nights.

But the glacier-bound uninhabited terrain has come to be associated with an equally incredible tale doing the rounds in India's top space and defence establishments - the sighting of an unidentified flying object or UFO at the Samudra Tapu region, a de-glaciated valley at an eight-hour trek from Chandratal.

WHAT IS A UFO?
A UFO or Unidentified Flying Object is defined as an object or optical phenomenon observed in the sky which cannot be identified even after a thorough probe. The accepted opinion of the mainstream scientific community is that probably all UFO sightings result from misidentification of natural and man-made phenomenon, deliberate hoaxes or psychological delusion.

A five-member team of glaciologists and geologists from SAC
WHO SAW IT?
A five-member team of glaciologists and geologists from the Ahmedabad-based Space Application Centre (SAC) of ISRO in September 2004, including (right to left) its leader Anil Kulkarni, geologists Rajiv Kalia, Sunil Dhar and SAC scientist Sushil Singh. The team had camped at Samudra Tapu, a huge de-glaciated valley.

UFO sighting
WHY IS THIS A UFO?
SIGHTING: Seen by all 11 members of the expedition. Scientific community has been unable to conclusively identify the object. PHOTOGRAPHS: The pictures taken by the scientists confirm that there was indeed something and they were not suffering from high-altitude hallucinations. FLIGHT: The object manoeuvred on ground and in air, defying gravity and wind direction, negotiated terrain, changed colour and took off vertically, the most challenging aspect of aviation technology.

Seen at Samundra region, HP
WHERE WAS IT SEEN?
SAMUDRA TAPU, a de-glaciated valley in Himachal Pradesh. A 12-km, eight-hour trek from Chandratal, it is approachable only via a 180-km deep trek from Batal, the nearest roadhead on the Manali-Leh highway. Kaksar, 70 km away, is the nearest inhabited town.

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More than a year after a five-member team of glaciologists and geologists had a 40-minute encounter with a balloon-shaped object straight out of The X-Files, the incident continues to baffle a section of the Indian scientific community.

Both Indian Space Research Organisation (ISRO) and the army are aware of the matter which figured even in Parliament last year when the minister of state with the Prime Minister's Office had, in a written reply, confirmed the ISRO report on the UFO sighting.

It was the penultimate day of a week-long expedition undertaken by Ahmedabad-based Space Application Centre (SAC) of ISRO on September 27, 2004. The team comprising three SAC scientists and two geologists had pitched camp in the valley some 17,000 ft above sea level.

They were studying the Chandra basin glacier using satellite data. Around 6.45 a.m., as the scientists were preparing to leave their tents, one of the porters spotted a white object on top of an adjacent mountain ridge, and screamed: "Sir, the snow man is coming."

Anil Kulkarni, a senior ISRO scientist who has been mapping glaciers for a quarter century, and his team members saw what appeared to be a robot floating a few inches above the ground, approaching the camp along the mountain slope. Kulkarni and his co-researcher, geologist Sunil Dhar, pulled out their digital cameras and began shooting the object even as the team raced towards the mountain to investigate.

The oblong object, between 3 and 4 ft high, kept moving down the slope towards the team. It had a cylindrical head with two balloon-type attachments, a body, hands and two legs. "It seemed to be walking, planting and pacing its steps like a human being," recalls Dhar.

It seems when the object reached the lower edge of the hill, 50 m away from the stunned scientists, the team members' excitement alarmed it. It stood still for a few seconds, turned and started a steep 70-degree ascent towards the ridge top. By this time, apparently due to the rays of the rising sun, its colour had changed to black. Soon it changed to white again, hovered above the camp for five minutes before noiselessly receding into a white dot in the sky.

Ever since 1947 when businessman Kenneth Arnold sparked off a worldwide UFO mania reportedly spotting flying discs, thousands of fake sightings have been reported from across the globe. It would have also been easy to write off the Samudra Tapu sighting as a mistaken aerial phenomenon except that it was observed and reported by a group of scientists willing to stick out their necks and reputations to swear by what they saw.

From the photographs, the UFO looks like a bunch of balloons caught in a mountain draft, but an SAC report claims the object displayed complex manoeuvrability. "It is a riddle beyond human perception," says Dhar who, along with Kulkarni, has contacted robotic labs across the world to determine what is technologically possible in unmanned flying vehicles.

THE USUAL SUSPECTS

UAVs

FOR: Unmanned (or pilotless) aerial vehicles are packed with electronic devices and are used for recce and spy missions.
AGAINST: UAVs are like aircraft which take off and ascend slowly. They can't climb or drop vertically, a feature the object showed.

Ballons
BALLOONS

FOR: Carry gadgets to measure atmospheric pressure, temperature and humidity. Accounted for most UFO sightings.
AGAINST: Even the most sophisticated weather balloons can't manoeuvre on land. The object negotiated land critically.

Airships
AIRSHIPS

FOR: Lighter than aircraft. Equipped with radar and used for military missions like early warning systems. Also used for leisure.
AGAINST: The object could manoeuvre like a human. It showed vertical takeoff capability, which airships do not have.

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"It didn't look like a man-made object," adds geologist Rajesh Kalia. Even more incredible is the photographic evidence-among the first in India for a UFO sighted on the ground- of the experience classified as a close encounter of the first kind in common UFO parlance.

Was it an unmanned aerial vehicle (UAV) on a cross-border spy mission or an extraterrestrial being? Or was it simply a helium-filled weather balloon which had lost its way? The jury is still out.

The scientists circulated the account of their close encounter in ISRO, army headquarters, Snow and Avalanche Study Establishments (SASE), an affiliate of Defence Research and Development Organisation which runs weather monitoring stations in high altitude regions, and among district authorities in Kullu. The army and SASE are the only agencies stationed in high altitude areas.

Perplexed, the scientists are now wondering if it could be something man-made. "But there is no known matching technology yet in the civilian realm to explain the mysterious object we saw so up close," says Kulkarni. Over the past year, Kulkarni and Dhar have been critically examining their sighting to deconstruct the object technologically, contacting top robotic laboratories in the US, Germany and Sweden. Kulkarni has shared his report with the director general of military operations.

Efforts to demystify the Samudra Tapu UFO sighting have made little headway, given the sheer high altitude, heavy snow cover and peculiar weather conditions which render the snowbound region virtually inaccessible for both air and ground expeditions. But the quest for demystifying the sighting has not stopped. "One way to understand the mysterious object is to undertake more expeditions in the area," says Dhar.

But the question is whether the object will ever be sighted again? "Unless the sighting is repeated, it will remain a puzzle," says Kulkarni. Till that happens, this is an enigma scientists may have to live with.